The invention pertains to an actuator/sensor assembly, and more particularly, to an actuator/sensor assembly which is mounted on a housing and having an actuator coupled to a sensor having a sensor shaft, and which may be mounted in an operating handle for a motor vehicle control.
There are numerous known sensors or detecting elements which can be mounted in housings. Rotary sensors generate signals which correspond to the rotary position of a sensor shaft. Such a sensor may be actuated by an actuator, such as a manually operated control knob directly mounted on the sensor shaft. However, such a direct connection is not always suitable or desirable for various reasons.
Swiss Patent Specification 647 053 describes a coupling between rotational bodies that are arranged in two different parts of a housing. The first rotational body consists of a roller that is arranged in an inner housing, with the rotational position of said roller being converted into electric data. The second rotational body consists of a shaft that is arranged in an upper housing, with a control knob being arranged on the end of the shaft which protrudes from the housing. The shaft is interlocked with the roller by means of a coupling. The coupling is composed of two parts. A first part of the coupling consists of a pin that is recessed into the roller and that is parallel and eccentric to the roller axis. A second part of the coupling consists of a disk that is concentrically mounted on the shaft and contains bulges that essentially extend in the radial direction and face the pin. The pin is situated between two adjacent bulges such that one of the bulges acts upon the pin when the control knob is turned such that the roller is also turned. This measure is also intended to achieve proper functioning of the coupling if the axes of the roller and the shaft do not coincide exactly.
Other types of sensors, e.g., potentiometers or encoders, contain a sensor shaft that protrudes out of the sensor casing and concentrically extends to a threaded section that is integrally formed on the sensor casing. A control knob for actuating the sensor is directly mounted on the end of the sensor shaft which protrudes out of the threaded section. Sensors of this type can be mounted on a housing by inserting the threaded section through a bore in the housing and screwing a nut onto the threaded section such that the housing is clamped between the sensor casing and the nut. However, transverse forces may be transmitted to the sensor shaft when the control knob is actuated. This can lead to faulty signals in sensitive sensors.
Accordingly, an object of this invention is to provide an actuator/sensor assembly which can be easily mounted on a housing.
A further object of the invention is to provide such an actuator/sensor assembly wherein transverse forces which act upon the actuating element are prevented from being transmitted to the sensor shaft.
Another object of the invention is to provide such an actuator/sensor assembly which can be used in an operating handle for a motor vehicle control.
These and other objects are achieved by the present invention, wherein a sensor has a sensor casing from which projects a rotatable sensor shaft. The sensor casing has a threaded section which extends concentric to the sensor shaft and which can be inserted into an opening in a housing. A bearing member is screwed onto the threaded section in order to clamp the sensor casing and the bearing member to the housing. An actuator/control knob is coupled to the shaft and is rotatably supported on the bearing member and consequently on the housing. Transverse forces which act upon the knob are absorbed by the bearing member and transmitted to the housing. Thus, the sensor shaft is not subjected to lateral loads from the knob. A coupler means transmits rotational movements between the knob and the sensor shaft and compensates for eccentricities between the axis of rotation of the knob and the sensor shaft.
The threaded section has a groove which receives a tab which projects from the housing in order to prevent an undesired rotation between the sensor casing and the housing. The bearing member has an outer cylindrical surface that corresponds to an inner cylindrical surface of the knob in order to rotatably support the knob.
Preferably, the bearing member has a cylindrical projection that faces the sensor casing, with the bearing member being supported on the housing by this projection. In the assembled state, this projection extends through a recess in the end surface (or side wall) of the knob. In order to ensure that the actuating element is freely rotatable and does not jam in the assembled state, the projection is slightly longer than the thickness of the side wall.
The knob preferably includes a sleeve-shaped actuating wheel and a cover that can be fixed to the end surface of the actuating wheel. The wheel has an annular groove in a cylindrical inner surface, into which the outer edge of the cover is snapped. The cover has a tab which projects radially outward and into a notch in the wheel, so that cover and wheel rotate together. A coupler couples the cover to the sensor shaft. The coupler transmits rotational movements between the knob and the sensor shaft and simultaneously compensates for eccentricities between the axis of rotation of the knob and the sensor shaft so that no significant transverse forces act upon the sensor shaft.
The sensor shaft and a recess of the coupler, through which the sensor shaft extends, both have essentially D-shaped cross sectional shape. The radial play between the sensor shaft and the recess in the direction transverse to the straight surface of the D-shape is relatively minimal in this case such that only a slight rotational play results during the transmission of rotational movements. However, the radial play in the direction of the straight surface of the D-shape is sufficiently large in order to compensate for eccentricities between the actuating element and the sensor shaft.
The knob or the cover includes a axial projections which are spaced radially outwardly from a central axis of the knob or cover. These projections engages a recess in the coupler. This recess may, for example, be formed by protruding bulges arranged on both sides of the projections in the direction of rotation. Alternatively, the projections may be arranged on the coupler and the recess formed in the knob. A radial play is also provided between the projections and the recess in order to compensate for eccentricities between the knob and the sensor shaft which are caused by the manufacturing process.
In the circumferential direction, the projection and the recess are adapted to one another in such a way that the smallest rotational play possible occurs during the transmission of rotational movements. Preferably, two projections are arranged opposite to one another on the knob or on the cover. These projections engage two slot-shaped recesses in the circumferential surface of the coupler.
This actuator/sensor assembly may be used in connection with an operating handles, such as an operating handle for motor vehicle control. The operating handle housing includes an opening through which the sensor shaft and the threaded section extend, and the knob is supported on the operating handle housing by means of a bearing member. Preferably, the operating handle housing is essentially hollow and encloses the sensor. The sensor shaft and the threaded section of the sensor extend outward through the opening in the operating handle housing. A bearing member can be screwed onto the threaded section in order to mount the sensor on the operating handle housing.